System of control



Aug. 28, 1923.

' 1,466,287 R. E. HELLMUND SYSTEM OF. CONTROL Filed March 11, 1919 5 Sheets-Sheet 1 ATTbRNEY Aug. 28, 1923. 1,466,287

R. E. HELLMUND SYSTEM OF CONTROL Filed March 11, 1919 s'sheets-sheet 2 INVENTOR RudO/f f. He/Imund WW (J L; %mu

' ATTORNEY WITNESSES:

R. E. HELLMUND SYSTEM OF CONTROL Filed March 11, 1919 5 Sheet-Sheet 5 WWG Elm

l WITNESSESI: g 8 INVENTOR Rudolf f. .l'lel/mund M I W W v ATTbRNEY,

Aug. 28, 1923. 1,466,287

1 I R. E. HELLMFJND SYSTEM OF CONTROL Filed March 1]., 1919 5 Sheets-Sheet 4 A III!!! IV Speed currenf e f WITNESSES: c INVENTOR MJMMw/" Rl/dO/ff Hal/mum ATi'ORNEY Patented Augr2 8, 1923. 7

air Sims- PATEN CE.

- genome swiss'vAiLE, r assignment, AssIeNoR To WESTING- o sn ELECTRIC &' MA UFACT RINGCOMPAN'Y,A CORPORATION or PE'NNSYL VANIA.

sYsrnM or CONTROL;

a piicatioir iiid'iiiarch 11.1919. Serial n0.;2s1,s55..

T 0 all who m a my concern:

Be it known that I, RUi)oL F HELL- MUN a citizen of the German,Einpire,.and

a resident of SWissvale, in the county of Allegheny and State of'Pennsylvania, have invented a. new and useful Improvement in Systems of Control, of which the following is a'spec-ilication.

My invention relates to systems of coir trol for alternating-current commutator D107 tors, andit has tor its object to provide relatively simple circuit arrangementsthat lend themselves readily toward effecting any desired speed regulation or power-factor adjustment, or both.

More specifically stated, it is one object of my invention to provide a singlepl1ase .coin- 'mutator motor having an inducing. field winding and an arn'iature provided with working-circuit and exciting-oi rcuit brushes,

together with a. suitable source of supply for the working brushes, and a; mutual impedance associated with the working and the exciting circuits to produce different speed characteristics of the motor in accordance with the particular connection of the iinpedance; In this way, the desired regulation of the motor circuits is satisfactorily secured, as.

will be evident from the following detailed description taken in conjunction with the accompanying drawings, wherein Figure 1 is a diagrammatic View of a system. of control organized in accordance with one form of my invention.

Figs. 2, 3, i, c, 7, 8,10, 11, 12, 13, 15 and 18 are similarviews of modifications of the invention.

Figs. 5, 9 and 1 1 are identical sequence charts, of well-known form, serving to indioate the order of operation of the relatively sinall'numbcr of illustrated switches.

'Fig. 16 is a sequence chart relating to the systems that are and 18. i

Fig; 1'? is a curve chart indicatingthc speed-current characteristics of those systems under various operating conditions.

Figs. 19 to 22, inclusive, are vector diashown in 15 grams graphically setting forth the relationsbetween various currents and voltages during the operation of the several systems.

The present systems are principally in-' tended for use in railway installations einfor the purpose of supplying energy through a pluralityol switches 1, 2 and 3 1n the order indicated by the sequence chart, Fig. 5, to an armature-excited, alternating current coinmutator motor 11 through the agency of a small-capacity transformer 12, a mutual impedance 13 being associated With'the working and the exciting circuits of the motor in a manner to be described.

. The illustrated alternating-current motor comp 'ises an armature- 14, of the coinin i, tator type, provided with one or morese ts of excitingcircuit brushes 15 and of working-circuit brushes" 16, the two different sets oi brushes, being locatediii electrical quadrature relation, and an inducingtield winding 17 the magnetizing of which is disposed in alinement with the magnetizing axis of the working-circuit brushes 16.

The transformer 12 is of relativelyisinall capacity andco nprises a primary winding 18 that isconnectedin parallel relation to the inducing field winding 17 to receive energy from the main source 10, a main secondary Winding 19 that is connected tothe Working-circuit brushes 16. and an auxiliary secondary winding 20 that is connected in circuit with the exciting-circuit brushes15.

The mutual impedance device 13 may be of any suitable form, being shown as comprising a plurality of coils 21 and 22 that are wouiidupon the legs of a common core and are respectively connected in circuit with the exciting brushes 15 and the workingbrushes 16 of the armature 14-. The

working circuit and the exciting circuit of the motor are thus inductively related through the mutualimpedance 13 for the above-mentioned regulating purpose. p

'The illustrated motor. is thus of the doubly-led or transformer conduction type having its inducing field winding designed for IOCOlVillg the l ul l voltage from the source of supply. The armature 14lcannot be built to witlistaiul :tull supply-voltage, but is connected to receive a suitable portion thereof from lhe main sccmidary winding 19 oi. the trzuisl'cu'nici' i2. The urrent travels in the exciting brushes 1:? is induced. by .he rotation of the armature 1.4. .in the flux of the inducing lield windinglT, tl'iereby produc ing a rotational voltage which may be com-- peusaled by a relatively low voltage supplied from the auxiliary secondary winding 20 oi the translorn'ier l2 to the exciting-ch.- cuit brushes l5.

The wiinlings oi' the mutual impedance 1?) may be connected in circuit in two dillierent ways. I t the magnetizing ell'ects ot the cur rents in the two coils during the motoring operation are dii'ierential or subtract the one from the other, then the machine will operate in accordance with a rather steep compound speed-current charactedstic curve and high power-factor.wili obtain even without the use of the auxilizury secondary traus- :iiormcr winding 20. Such a steep speedcharacteristic curve is especially advanlagoons during 'regenerative operation. wlu as is the case in railway vehicles, a negative compound char-actmristic, that is, an increase of excitirg lield current to accompany a decrease ol armature current and. vice versa, is dcsi red. On the otl'ie'r hand, if too (:lllI'GUt-S in the two windings 21 and 22 of the mutual in'lpedancezu'e caused to combine additively, then the machine will run in accordance with a relatively flat speed characteristic, which very desirable in some railway installations. The vectorial relation of the various currents and voltages in the system are shown in a general. way in Figs. 19 to 21, inclusive, under 'arious ope 'ating conditions, and will be described. later by way of illustrating the previous statements with respect to the type of speed characteristic that obtained during the operation of the various illustrated systems.

it will be understood that I have illustrated only the minimum number of switch ing devices that necessary to bring out the important teaturcs of the present inven tion. During the starting operation oi? the motor, switches l and 2 are closed, as indi rated in l i whereby the motor is accelerated in at dance with a series characten the armature current corresprmding to the sum (it the current in the inducing lield windi r l? an l in the primary winding 18 of the tra former 12. The circuit connections 'for s y ting may be briefly traced as follows: 'lroin the left-hand terminal of the source oii supply 10, through switch and the inducing field winding 1 and the primary transformer winding 18, in parallel relation, whence circuit is continued tltirough the auxiliary secondary trans- :l'ormer winding 20, the impedance coil 2i, the exciting circuit brushes 15 and switch 2 to the op iesite terminal. ol the source 10. At the same time, another circuit is established from one terminal ol the main secondary winding; 19 of the transformer 1:! through the working-circuit brusheslG oi the i'notor and the impedance coil 22 to the other terminal oi the transtornicr wind ing 19.

For running conditions, the switch 8 also is closed, whereby the right-hand terminal or no. inducim;- field winding l? is connected directly to the right-hand. terminal ol thc source 10. In this way, the inducing lield wirnling is connected across the source 01 si'lpply, while a new separate-excilation circuit is formed simultaneously, including the exciting brushes if), the impedance coil Zl, the auxiliary t'ansiormer winding 20 and the switch.

The system shown in Fig. 2 differs from that Fig. .1. in the-direct connection of the main secondary t'ans'iormer winding 19 to the working-circuit brushes ll); the connec tion oi. the primary transforn'ier winding 1n and the inipedai'ice coil 21. in series relation across the main source of supply 10; and. the connection. o i? the auxiliary secondary t anstiormer winding 20 in series relation with the inducing field winding .17, the impedance coil 22 and the exciting brushes l5 ol' the armature for starting the motor.

In the present instance, the inducing-field winding current alone enei es the arlna tiire-exi'zil'ing circuit during starting conditions when the switches 1. and 2 are closed; while, duringrunning conditions, the switch 3 is closed to connect the inducing lield winding directly across the source of supply l0, and the mutual. impedance 153 is as sociated with the armatureexciting circuit and the primary winding of the transl'ormer 12, in a manne analogous to that previously minted out.

in 3, the indiiicing field winding 1T shown as comiccted to the up er e. :citing circuit brush 15, whereby the field windiin); is directly connected across the source 1 under starting conditions corresponding to the closure of switches 1. and 2, while the ren'iaining circuits are similar to those shown in vFig. 1., with the exception of the inter change ot the impedance coils 21. and 22.

in the system of Fig. 3, the current traversing the primary winding 1.8 of the transformer i2 is cnnaloyed for starting the mo tor by t 'avcrsing the exciting circuit brushes 1. while the mutual impedance coils 21. and 22- again serve to inductively associate the working circuit of the armature withthe nviting circuitthereof.

In F' l, the inducing field winding 11' is a ain connected. to the u er excitin -circuit brush 15, while the secondary windings working-circuit brushes 16 and the excitingcircuit brushes 15. An inductive device24 and a resistor are connected in the main armature lead between the upper exciting This brush 15 thereof and the switch 2. I arrangement serves equally Well with, those previously illustrated, employing the mutual impedance 13, for the desired regulating'operation, since the armature-exciting current and the inducing-field-winding current both traverse the inductive device 24: and the resistor For starting, current is supplied from the primary transformer I winding 18 through the excitingcircuit brushes 15 of the armature, while, upon the closure of switch 8, during running conditions, the primary winding .18 is connected directly across the source of supply. It will be noted that the armature-exciting currents and the inducing lield-winding currents are .cumula tively related in the circuit comprising the inductive device 24 and the'lresistor 25.

However, in Fig. 6, theinductive device 24 is connected to carry the difference of these two currents." This result. is accomplished by connecting the running switch 3 and the inductive device 2 1 between the right-hand terminals of the, inducing field winding 17 and the primary winding 18 of the transformer '12, instead of in the po sition that is shown in Fig. 4. Under such conditions, when the switch 3 is closed, an exciting current circulates through the excit ing hrushes'15, the skinny" transformer winding 2O and the i.ndiictiveclevice 24; IA load current flows through the. deyice 24L and the primary transformer windingltid I flhiis, the inductive coil 24' carries two currents; having a direction and a inagnitiidethat a -re dependent upon the relative characteristics of the inducing field Winding 17, the trans? former winding 18, the armature winding 11, etc, as will he understood. 4 I

The system of Fig. 7 includesthe connections of the inductive device 2land the inducing field winding 17 in the saiiie locations as shown in Flg. l, Wl'11l(-} the resistor I i I I,

25 is connected in the same position as the inductive device 241 in Fig. 6. I Consequently,

the inductivedevice 2t carries the sum of.

the armatureexciting and the" inducingfiel d-wii'iding currents, as indicated by the fact that the illi'i sti'ated solid and, dotted arrows point'i n thee in direction, while these currents renew o 'bp o'sitei paths in the resistor as indicatedby th e coriesponding arrows, when the switch 3 is" closed during running conditions of the motor.

Referring to Fig. 8 the mutual impedance 13 is connected to indiicti elyinterlink the ai'matuieexciting circuit (bi-ashes 15) and the new e middle 1ead26 0f the illustrated doubly-fed motor, which employs the main secondary winding 19 of the transformer 12 for the purpose of supplying energy to both the inducing field winding 17 and the armature workingcircuit including the brushes Under ,starting conditions, I with the switches land 2 closed, a current. traverses the primary transformer winding 18, the impedance co l 22 and the exciting-circuit iliary secondary transformer winding 20 are connected in series relation across the main source of supply, a while the transformer winding 20 is also connected through the impedance coil across: the exciting-circuit brushes 15 to supply energy thereto.

Fig. 10 adds, to the system of Fig. 8, the resistor 25 whichiisconnected in parallel relation to the impedance coil 22 in the ex citing circuit of the armature to render I variable the ratio between the currents traversing the armature-exciting circuit and the middle lead of the doubly-f d motor; while the inductiyedevice- 24 is connected between the switches 2 and 3 in circuit with the auxiliary secondary transformer winding 20, thus providing a mutually inductive effect, as regards the current of the primary transformer winding 18 and the excitin current of the armature. I

In Fig. 11, a stator-exciting field winding 30 is employed in addition to the exciting circuit including the armature brushes 15. the exciting field winding being connected in series relation with the inducing field winding 17 across the source of supply, when the switches 1 and2 are closed. In addition, an auxiliary transformer 27 has its primary-winding 28 connectedin series relation with the impedance coil 22 across the source 10, while the secondary winding 29 of the transformer 27 is connected directly to the working-circuit brushes 16.

Under starting conditions, therefore, the stator exciting field winding 80 provides the entire field excitation for the motor, but, upon the closure of switch 3 during running conditions, the exciting-circuit brushes 15 are connected through the impedance coil 21, whereby a certain supplementary armature excitation is set up and, furthermore. the desired mutually inductive relation between the exciting current of the armature and the current traversing the primary transformer winding 28 obtains. I

In F 12, the resistor 25 is substituted for the two impedance coils 21. and 22 to again iii) and the stator field winding 30 is also en1- ployed alone during starting conditions of the motor and togethei with the exciting-c1r cuithrushes 15 during runnii'ig conditions. in Fig. 12%, the stator field winding: 30 omitted. ilhe pri ia y ti. -xl'm'n'uir winding is connected dircctlv through the ext-ii,- :inc wircuit hr shes across the main sourk-e of supply during star-tug conditions i the motor. while the inductive device 2i .ocation as the resistor 25 of Fig. 1%, namely,

a ross the excitingncircuit luiushes during running; conditions, when the switch 1-) is closed.

l n Fifi. 15. a. transformer motor is connected in circuit with a mutual inductance 31 that acts hctwee the circuit of the inducing field winding 14 and the exciting; circuit ol the armature int-hailing the brushes In this case the worlcingr circuit hrishcs 16 are short ciriruited. energy heing transferred to the worlzi n51 circuit solely through the trans- ;toriuer action 01 the ind field windin the armature \"lllk inc;

inductive device ill is en'iploycd in during 'arious Sta -2 of the dil 'ercn t ways 7 iuol 1 i detcrunned y the order z' operai ion as sper itiou ot the switches l to 5. inclusi is indicated in the sequence chart,

ill, for the purpose oi providi i ics oi speedscurrent cu rves wherehy :1." i

veuient method of motor aci-clcratien iorded.

fxt the outset, switches l, 2 and Z? are closed, as indi rated hy step n. of, the sei'uici'icc chart. Fig. 16. circuit being; therein; established from the le1tt-haud terminal oi? he source of supply l0 through switch l. (he inducing: cue winding 17. switch 3. the lower section ii of the imluctive device 31..

active device in this case the 1g ell'ect oi" ll nductive device is lly proportiona to the li'll'creuce load and the e'iclting currwis of the which gives a 'lairly sleep compound cluiracteristic to the motor. as shown h) curve ll.

In step c, the switch 5 is closed to shortcircuit the upper section 32 ot th inductive device 3t, rendering the device substantially nondinluctive by reason of the concurrent closure of the switches 23, 4tand .5 and the 'lirus relation of current flows in the various portions oi the inductive device. Under such conditions a shunt speed-current cliaracteristic is imparted to the motor, as illustrated by curve C.

For the iinal step (Z of the controller, the switch is opened to reverse the relative direction of the armature exciting currents and the ind'uch lield winding;- or load cur-- out. in the indu Live device Bl. therehy produciugg a relatively flat speed charmieristic shown by curve D.

. the motor is accc erated through the recited steps in accordance with the hroltcn line r f lzi iilil oi." Fig. l7. it evident that a is nooth acceleration, involving); no current reps at unduly large size, may he ohtained. h the final speed cluu'a-ccerisiic very flat. 4

Fig. 18 shows the principles of Fig. 15 as applied. to a douhhx-cted mote:- the same order oi operation of the illustrated Switcher-s ennployed for accelerating the motor. he noted that the inducing field wine lllif l]? is coun cted directly acres-.1 the scene of supply it) when the switches l. and are closed; while the evcitiug circuit tor the motor is 'hlished, during unui'n;- coaili lions. 'lroiu the switch t throug 'l-i the exciting hi, the indiuxtivc-coil section Elli and rtion ot' the section 3 The working-- circuit hrushes l6 are'counected across the secoi'ulary "viudingi l9 oi the translmmer iy reason ol the similarity o'l' operation of he ssilein illustrated in Fi 18 to llut shown in Fig. 15, no il urther description s deemed necessary.

It has previously been mentioned that the illustrated mutual inductive or translating dev ccs will provide a steep (TOIHPUHJ(hspOW current characteristic for the motor it the magnetizing effect of the inductive device corresponds to the diflj'erence between the er"- citing and the load currents of the motor. whereas a atl'ier flat curve is obtained when the magnetizing eltcct corresponds to the sum of those two currents. These statements may he graphically demonstrated by means of Figs. 10 to 22. inclusive. In Fig. 19

I the load current of the motor.

I; z the magnetizing; current flowing through the exciting brushes 15 (of F 15, for exan'iple). Therefore, the vectorial ditlerence of these two currents or the magnetizing current flowing through the inductive coil when the magnetizing current in the. inductive device is equal to the difference between the exciting and load currents of the motor, as in condition 6 of the system shown in Figs. 15 and 16. E the voltage impressed upon the motor circuit including the inducing field winding 17.

.F, the counterelectro1notive "Force that is set up in theinducing field winding. by the, portion of the fluxwhich threads the armature thereof. 7

cf. (1. and a. resoccti elv the ohmic. the.

reactive and ,the resultant impedance drop thatis caused by the line -inductivecoil inducesa voltage E la ing in to substantially 90 in phase relation thereto. By adding the voltage E to the inducing, field-winding voltage E I obtain the total resultant countcr-electromotive force of the motor, minus voltage E which equals the total impressed motor voltage E The vector E represents the rotational voltage that is set up by the inducing-field winding flux in the armature between the exciting brushes 15, and lags substantially 90 beh nd the counter-electromofive force Fi of the inducing field windin By subtracting'th'e inductivedevice volt age E. from the voltage sultant exciting; circuit voltage Fi which leads the exciting current I by an angle slightly less than 90. I i I Fig. 20 shows a similar set of vectors, ex cept that the load current I has been assumed. of a very much smaller value. j'lhis condition gives a relatively large inductivecoil magnetizing current I and inductivecoil voltage E which voltage extends in a direction close to that taken by the rota tional voltage vectorE and produces a much smaller voltage E. for the exciting cir cuit. By comparing the diagrams of Fig. 19 and Fig. 20, it will be seen that the field excitation is smaller and the motor speed is higher when light-load conditions obtain.

Figs. 21 and 22 illustrate the case wherein the magnetizing effect of the inductive device corresponds to the cumulative effect of the exciting and the load currents of the inotor or, in the diagram, assuming that the load current I and the exciting current I both magnetize the inductive device in the same direction. In this case, it will be seen that the inductive-device voltage E extends in approximately the opposite direction to the rotational voltage l6... and thus Jpractically subtracted therefrom to produce the exciting-circuit voltage Fi Upon comparison of Figs. 21 and 22, it is further evident that, with a decreased load current I as shown'in' Fig. 22, I and E also decrease and, therefore, the excitingcircuit voltage E; islarger than in Fig. 21.

no in the 7. obtain the rcln otherwords, it'is obvious that the exciting-circuit voit F1 and the corrr ins; i'nlrcnt ll increase with a educl' load, while the counter-electroniotive l'orce l3. o lbe indu ing iieldwinoi 17 remains substantially constant, thus pi 'duction, of exciting field strength upon an increase of load and, therefore, a very flat or, in some cases, a risingspeed-current "characteristic; 7

do not wish to be restricted to the specific circuit connections or arrangement of parts herein set forth, as various modifications thereof may be made without departing from the spirit and scope of my invention.

I desire, therefore. that only such limitations shall lie-imposed as are indicated in the appended claims. Y

I claim as my invention:

1.1Tl16 combination with an alternating current commutator motor'having an inducing field winding and an armature provided with working brushes and exciting brushes, of a main source of supply, an auxiliary transformer having single primary winding energized therefrom and having a secondary winding connected in circuit with said exciting brushes and another secondary winding connected in circuit with said workingbrushes. and a oviding' a iemutual impedance having two inductively related coils respectively cuit with thesets of -l rushes.

The c, bination with an alternat'in52;- current comn'n'itatm' motor having); an inducing: field winding and an armature provided with working brushes and exciting brushes, of a main source of supply, an auxiliary transformer having a primary wind ing connected across said source and a separate secondary winding connected to said working brushes. and a mutual impedance having two inductively related coils respectively connected in circuit with said secondarvtransimaner winding and with said exciting brushes.

3. The combination with an alternatingcurrent commutator motor having; an in ducing field winding and an armature provided with sets of workin; brushes and exciting brushes, of a main source of supply, an auxiliary transformer cnergi ail therefrom and having a winding associated with one of said sets of brushes, a mutual impedance having two inductively related coils 1.'es )cctivcly connected in circuit with the sets oi ln'ushcs, said inducing winding being initially connected t said transformer and said impedance, and means tor subsequently connecting said inducing winding directly across said source.

4. The combination with an alternatingcurrent commutator motor having an inducing field winding and an armature pro vided- With working brushes andexciting connected. in cir brushes, of a main source of supply, an auxiliary trans'toriner CHQI'QJZOCl therefrom and having: {two secondary 'wlndlngs, one ot which is initia ly connected to the working;-

circuit brush inn two indu a mutual impedance hav- Vyely relat l cons respec- Lively connected in circuit with the sets of brushes, said inducing winding being initially connected in circuit with the other secondary Winding; and with one oi" said coils and means for concurrently connect with working brushes and exciting brushes, of a main source of supply, an auxiliary trans' former energized therefrom and having a primary Winding connected in parallel relation to said inducing windiinr and. having two secondary windings, one of which is initially connected to the worlzingg-circuit brushes, a mutual impedance having two inductively related coils respectively connected in circuit with the sets of brushes, said inducing winding: and said primary transformer winding being initially con nected in circuit with the other secondary Winding and with one of said coils, and means for concurrently connecting said inducing Winding and said primary transformer winding across said source and connecting said other secondary winding across the exciting brushes under running con ditions of the motor.

In testimony whereof, I have hereunto subscribed my name this 1st day of Marcln 1919.

RUDOLF E. HELLMUND. 

